A golf ball is composed of a core and a cover covering the core. The cover generally used is mainly formed from an ionomer resin (see Japanese Kokai Publications 135078/1984 and 82768/1986), because the ionomer resin is commercially available cheaper than the other cover resins and has excellent cut resistance.
The ionomer resin is a resin which is prepared by neutralizing a copolymer of an alpha-olefin, an alpha, beta-ethylenic unsaturated carboxylic acid and optionally an alpha, beta-ethylenic unsaturated carboxylic ester with metal, and many types of them are commercially available. The ionomer resins which are used as the cover of the golf balls, however, contain the alpha, beta-ethylenic unsaturated carboxylic acid in an amount of less than 15 % by weight before neutralizing, and the other carboxyl-rich ionomer resins which contain more than 15 % by weight of it have never been employed.